This invention relates to novel 5- or 6-substituted .beta.-carboline-3-carboxylic acid esters.
Numerous patents have described .beta.-carboline-3-carboxylic acid esters, for example, EP Patent 30,254 which discloses closes the .beta.-carboline-3-carboxylic acid isopropyl ester and the .beta.-carboline-4-ethyl-3-carboxylic acid isopropyl esters. DOS 3,332,895 which describes the 5-[1-(4-chlorophenyl)-ethoxy-4-methoxymethyl-.beta.-carboline-3-carboxylic acid isopropyl ester (See U.S. Ser. No. 623,610, of Jun. 22, 1984); and U.S. Pat. No. 4,435,403, relating to the 5-benzyloxy- and 6-benzyloxy-4-methoxymethyl-.beta.-carboline-3-carboxylic acid esters. These references further disclose genera which generically overlap a portion of the genera of this application. All of these references are entirely incorporated by reference herein. It can be seen from these that .beta.-carboline-3-carboxylic acid esters affect the central nervous system and are suitable as pharmaceuticals.
.beta.-Carboline-3-carboxylic acid ethyl esters are cleaved with relative ease into the corresponding acid by appropriate enzymes; these acids exhibit no affinity, or only a slight affinity, to benzodiazepine receptors.